Overview

A search display controller manages display of a search bar and a table view that displays the results of a search of data managed by another view controller.

You initialize a search display controller with a search bar and a view controller responsible for managing the original content to be searched. When the user starts a search, the search display controller is responsible for superimposing the search interface over the original view controller’s view and showing the search results. The results are displayed in a table view that’s created by the search display controller. In addition to the original view controller, there are logically four other roles. These are typically all be played by the same object, often the original view controller itself.

1. The search results table view’s data source.

   This object is responsible for providing the data for the results table.

2. The search results table view’s delegate.

   This object is responsible for, amongst other things, responding to the user’s selection of an item in the results table.

3. The search display controller’s delegate.

   The delegate conforms to the UISearchDisplayDelegate protocol. It is notified of events such as when the search starts or ends, and when the search interface is displayed or hidden. As a convenience, it may also be told about changes to the search string or search scope, so that the results table view can be reloaded.

4. The search bar’s delegate.

   This object is responsible for responding to changes in the search criteria.

Typically you initialize a search display controller from a view controller (usually an instance of UITableViewController) that‚Äôs displaying a list; you set self for the search display controller‚Äôs view controller and search results data source and delegate:

searchController = [[UISearchDisplayController alloc]

                         initWithSearchBar:searchBar contentsController:self];

searchController.delegate = self;

searchController.searchResultsDataSource = self;

searchController.searchResultsDelegate = self;

If you follow this pattern, then in the table view data source and delegate methods you can check the methods’ table view argument to determine which table view is sending the message:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    if (tableView == self.tableView) {

        return ...;

    }

    // If necessary (if self is the data source for other table views),

    // check whether tableView is searchController.searchResultsTableView.

    return ...;

}